Huang et al. examined the expression of CPA4 mRNA in 16 normal human tissues by Northern blotting but failed to detect expression in heart, brain, placenta, lung, liver, skeletal muscle, kidney, pancreas, spleen, thymus, prostate, testis, ovary, small intestine, colon, and peripheral blood lymphocytes except prostate cancer cell lines [7]. This evidence concerns the gene CPA4 and prostate cancer.